Meet Sung Soojung, the ultimate badass. She has been trained since the age of 5 to work as a spy in South Korea. She has worked in the navy and the marines and taken part in many terrorist takedowns. She's been given the title of best rookie spy at her bureau. Now at the age of 18, she is taking part in her first professional spy investigation. She must investigate a corrupt business firm, Kim Corporations. In order to do so, she must go to high school and befriend Kim Corporation's son and inheritor, Kim Jongin. Can she succeed in her first mission? Are there pieces missing to the puzzle?